This study investigated the group invariance of equating results using a science achievement test. Examinees were divided into different subgroups based on the average composite score for test centers, whether they had taken a physics course, and self-reported science grade point average. The reason for dividing examinees into subgroups using such variables is that those variables are more related to performance on a science achievement test than, say, gender. Results indicated that the conversions obtained from different subgroups were similar to the conversions obtained by using the total group, except when the groups were divided based on whether a student had taken a physics course. Where there were differences, the differences were generally 1 equated raw score point. (Contains 10 figures and 5 tables.)